Derivation of the Buoyancy Ratio Equation from the Bubble Migration Model

摘要

Most Hanford waste tanks do not have buoyant displacements, even those with deep submerged sediment layers and moderate gas generation rates. Most tanks apparently achieve a steady state where gas generation is balanced by a steady background release so they never attain the neutral buoyancy gas fraction. In a few tanks, however, gas generation exceeds the background release, which allows gas to accumulate to the point of buoyancy. The mechanism for this background release is unknown, but we postulate that the background release is a slow migration of bubbles through the sediment. This document, an addendum to PNNL-13337, 'Preventing Buoyant Displacement Gas Release Events in Hanford Double-Shell Waste Tanks,' presents the derivation of the equation in the Bubble Migration Model that explains buoyancy.